The present invention relates to a novel organopolysiloxane having alcoholic hydroxy groups and a method for the preparation thereof.
There are known, in the prior art of silicones, various kinds of organopolysiloxane compounds having an activity as a surface active agents. They are classified roughly according to the nature of the hydrophilic groups with which the silicone compound is modified into four classes of those compounds having anionic, cationic, amphoteric and nonionic hydrophilic groups.
Among the above named four classes of the surface active compounds, in particular, the nonionically hydrophilic groups include oxyethylene groups obtained by the ring opening of ethyleneoxide having an H.L.B. value of 0.33 and alcoholic hydroxy groups having an H.L.B. value of 1.9 and the surface active organopolysiloxane compounds of the most widely used nonionic type are the so-called polyether-modified ones having the oxyethylene groups as the hydrophilic groups.
On the other hand, there are known few nonionic surface active organopolysiloxane compounds in which the hydrophilic groups are the hydroxy groups derived from polyhydric alcohols. The only example of such surface active organopolysiloxane compounds is disclosed, for example, in Japanese Patent Publication 48-19941 according to which a methylhydrogenpolysiloxane and an aliphatic polyhydric alcohol or a polyoxyalkylene alcohol are subjected to a dehydrogenation reaction to introduce the alcoholic hydroxy groups into the organopolysiloxane to form a surface active silicone compound useful as an additive in toiletries.
The above described nonionic surface active organopolysiloxane compound is obtained by the dehydrogenation reaction between a methylhydrogenpolysiloxane and a polyhydric alcohol to introduce the hydrophilic groups into the polysiloxane but great difficulties are usually encountered in carrying out such a dehydrogenation reaction because the reaction mixture may readily be gelled in the course of the reaction so that the desired product can hardly be obtained in an industrially significant yield.
Another problem in carrying out the above mentioned dehydrogenation reaction is the difficulty in obtaining a suitable solvent capable of dissolving both of the reactants. For example, the use of toluene and other hydrocarbon solvents most widely used in the synthetic preparation of silicones is limited as a solvent for an alcohol having a relatively long hydrocarbon group such as lauryl clcohol and stearyl alcohol and the dehydrogenation reaction with a strongly hydrophilic polyglycerol and the like as one of the reactants can hardly be practiced due to the insolubility of the polyglycerol and the like in toluene or other conventional solvents.
Therefore, there has been developed almost no promising way for the preparation of nonionically surface active organopolysiloxane compounds in which the hydrophilic groups are the hydroxy groups derived from a polyhydric alcohol notwithstanding the eager desire to develop novel and useful applications of such a surface active agent.